Classifications

• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
  • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
  • G07D7/16—Testing the dimensions
  • G07D7/164—Thickness
• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
  • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
  • G07D7/06—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using wave or particle radiation
  • G07D7/12—Visible light, infrared or ultraviolet radiation
  • G07D7/121—Apparatus characterised by sensor details
• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
  • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
  • G07D7/20—Testing patterns thereon
  • G07D7/202—Testing patterns thereon using pattern matching

Definitions

• the invention relates to a method for verification of security documents and a verification device for security documents, which perform a Wei ßlichtinterferometrie and use to existing in a security document
• Security features may thus be all features that make duplication, unauthorized production, tampering or other manipulation of a document or item difficult, impossible, or at least make a precise examination of these undesirable actions verifiable.
• Security documents are all documents that have at least one feature that make duplicating, copying, falsifying or other manipulation difficult or impossible.
• Security documents include, for example, passports, identity cards, driving licenses, access cards, visas, but also labels for high-quality products, such as software, tickets, but also bank cards, credit cards, phone cards or the like, as well as documents that embody a value, such as stocks, securities, banknotes, Postage stamps, customs stamps and others, just to name a few examples.
• Security feature serve.
• the different printing methods which are hard to imitate or reproducible in part or in combination for a counterfeiter or manipulator can serve as security features.
• In the production of security documents almost all current printing methods, such as intaglio printing,
• High-pressure process but also ink-jet printing process or offset printing process, used in their different forms. These usually show one typical characteristic print image, which differs from the printed images produced by other printing processes at least at a microscopic
• security features include diffractive structures, relief structures, special colors and the like.
• modern security documents which comprise a document body made of one or more plastic materials, a plurality of different security features in a document body made of one or more plastic materials, a plurality of different security features in a document body made of one or more plastic materials.
• Enable security documents Such a procedure is called verification.
• Verification devices known, which are usually adapted to special security features and provided for their verification. It is desirable to provide new verification methods and verification devices that can be used for a variety of security features and / or security documents to verify their authenticity and authenticity.
• a verification method which uses a white light interferometry to non-destructively examine a surface structure as well as an internal structure of documents.
• Verification can be carried out with a verification device comprising a white light interferometer, which is designed to create a depth profile of the security document at least at one point. This does not necessarily extend over an entire extent along a direction of examination of the security document. This means that a depth profile does not have to penetrate the entire document. This is For example, in documents comprising opaque layers or metallically reflecting layers, not possible by means of a white light interferometry.
• a method for verifying a security document comprising the steps of: orienting the security document relative to a white light interferometer, performing a white light interferometric
• Such a method can be implemented with a verification device which comprises a document holder and a white light interferometer which is designed to create a depth profile along at least one position on a surface of a security document arranged on or in the document holder along an examination direction oriented transversely to the surface. and further comprises an evaluation device which evaluates the at least one depth profile.
• any optical interferometric device As a white light interferometer, any optical interferometric device is considered, which brings broadband light with spatial coherence to the interference and evaluates this interference. It is irrelevant whether this light spectrum in the visible wavelength range, infrared wavelength range or UV wavelength range is arranged wholly or partly.
• a depth profile measurements of a physical quantity associated with different depths along an examination direction are considered, the examination direction being in an interior, i. the volume of a body, such as a document, extends.
• a depth profile begins outside or on the surface of the object into which the
• a depth profile is a position on a surface of the examined object, for example a security document, assigned. The position is that on the surface where one of the
• Depth values are the distances along an examination direction, along which a depth profile is created, based on a reference value.
• a reference value the point of intersection of a straight line indicating the examination direction with the surface of the document support or any other surface perpendicular to
• the examination direction is the direction along which the light impinges on the surface of the object to be examined. In doing so, local unevennesses of the surface are disregarded.
• Measurement information is referred to as intensity value.
• deriving a feature By deriving a feature is meant deriving a quantity or any abstract or mathematical object or construct, for example a vector of intensity values, or a group of depth value intensity value tuples.
• the set of depth values and intensity values, or a selection thereof, as well as a value resulting from a statistical evaluation represents a derivative of a feature.
• An intensity value change is a value assigned to a depth value of a depth profile and which is compared to one or more
• the intensity value change is determined by a comparison with the intensity value corresponding to the neighboring depth value or neighboring depth values in the same
• Depth profile is or are specified.
• the intensity values of adjacent surface positions and equal or adjacent depth values may also be taken into account. Preferred embodiments
• the invention offers the advantage that structures occurring on the surface or in the interior of a security document, which can occur at different depths of the document transversely to the surface, can be verified. For example, it can be determined at which level one of transparent
• Plastic document material produced a perceived as blackening for a human viewer information is stored.
• Document body can be stored, in terms of the spatial design of the information-carrying components of the security document. If the information is printed, for example, on a substrate layer which is subsequently laminated with further substrate layers to form a document body, the information is located in the vicinity of an at least originally existing layer boundary. On the other hand, if the information is introduced via a laser marking process, a larger volume range is usually inked via a partial carbonization of the plastic material. In the depth profile can be seen at what depth the information is marked, so that a printing process can be distinguished from a laser marking process. Laser marking methods are also sometimes called
• the security document is preferably oriented so that the
• Examination direction which is determined by the incident on the security document white light of the white light interferometer is oriented perpendicular to a surface of the security document.
• the surface is here the
• Security document which has the largest areal extent.
• such an orientation can be achieved simply by configuring the document receiver so that it is in or on it
• the arranged security document is automatically oriented with its surface perpendicular to the examination direction.
• the document holder can be designed as a support surface, which, for example, by a virtually no Absorption in the wavelength range, having a transparent, plane-parallel plate is formed, on which the security document is laid flat or pressed with its surface to be examined or pressed. An impressing ensures that the
• Light source a beam splitter, a detector, one on a controllable
• Linear actuator mounted reflector and a control and data acquisition device wherein the light source broadband, having a spatial coherent light and is arranged with respect to the beam splitter that the beam splitter directs a portion of the light in a measuring arm, in which the object holder is located, and a Part of the light passes into a reference arm, in which the reflector is arranged so that the light is reflected back onto the beam splitter and superimposed there with the light, which is arranged on a in or on the document holder
• Security document is reflected back to the beam splitter, wherein the detector is arranged so that this one in the superimposition of the reflected light of the
• Reference arm can detect with the reflected light of the measuring arm resulting interference signal, wherein the control and detection means is coupled to the linear actuator to vary during the detection of the interference signal, a reference arm length over a linear displacement of the reflector, the reference arm lengths correspond to Messarmin, the Corresponding distances from the beam splitter along the examination direction, at least to the surface of the
• Security document on and in the document recording or into the inside of the document recording correspond.
• the variation of the reflector position thus varies a reference arm length of the interferometer.
• the light in the measuring arm hits the surface of the object to be examined, i. of the security document, and also penetrates at least partially into the security document. Both at the
• portions of the examination light in the measuring arm are reflected back into the interferometer in the security document.
• portions of the examination light in the measuring arm are reflected back into the interferometer in the security document.
• Reference arm length which on the position of the reflector (for example, a
• Reference level is determined, which portions of the light along the Inspection direction in the security document are reflected back into the interferometer, leading to a constructive interference at the detector.
• the reflector position in the reference arm thus determines the depth, which is scanned by the resulting interference.
• monochromatic light is not used, but rather broadband, spatial coherence light is used, the resulting interference pattern is much more complex.
• computational algorithms are known from the prior art, which make it possible, a depth profile along the examination direction from the temporal succession
• OCT optical coherence tomography
• OTC optical coherence tomography
• the white light interferometer is thus preferably designed as an optical coherence tomograph.
• depth profiles are determined for multiple locations on the surface of the security document.
• multiple locations that are co-located along a path on the surface of the security document or multiple locations located in a surface area of the security document surface that includes the at least one location coincide with the depth profile for the at least one location recorded depth profiles.
• Depth profile is detected at the same time.
• the detector for each of the locations to be detected to comprise a light-sensitive detection element in order to be able to detect the interferences assigned to the individual locations and to be able to derive the corresponding depth profiles for the individual locations. If the light is widened along two spatial directions, it is possible to record the depth profiles simultaneously for locations in a surface.
• the detector does not have to be just one linear array of photosensitive sensors, but have a flat array of photosensitive detection elements, which can detect for the respective locations in the surface each of the interference signal during the variation of the reflector position.
• Display device determined at least one of the detected depth profiles
• Investigation direction and the distance or a lying in the surface area contour is clamped.
• Cross-sectional area side by side illustrated depth profiles also correspond to points that are spatially adjacent to each other on the surface.
• One advantage of such a cross-sectional representation, which, for example, along a path represents a cross-section through a volume area in the interior of the document transverse to the surface of the document, is that
• Substrate layers joined together in a lamination process It is not always possible to carry out this lamination process in such a way that a monolithic document body exists in which the original layer boundaries in the solid body can no longer be detected by measurement as phase transitions.
• a printing layer produced by high pressure thus shows characteristic height profile properties resulting from the
• Substrate layers connects.
• the colorants used do not necessarily remain on the printed surface, depending on the specific composition of the printing ink used, but optionally diffuse specifically into the substrate layer to which the print is applied.
• pressure ranges generated by means of such an ink jet printing method can thus be clearly differentiated from other pressure ranges.
• Delamination of a document body are associated, and / or optionally a planing and / or new insertion of material, inserting altered or corrupted other security elements, such as metallized films or patches of other types or holograms, are associated with the proposed verification process recognizable when joining and / or inserting usually not the same process parameters are used, which in the
• depth profiles or cross-sectional areas formed from these can be stored as defaults in a database or memory as defaults.
• the intensity values and / or intensity value changes corresponding to individual depth values or depth ranges are evaluated statistically with regard to the frequency in order to determine a deviation from an expected statistical distribution as an indication of a manipulation or forgery.
• a depth range for example, an area adjacent to a
• Layer transition can be selected in the document in which at a not
• Intensity values and / or intensity value changes occur.
• characteristic intensity values or intensity value changes also occur with depth values which do not correspond exactly to the depth of the layer transition, such as in a forged security document will, for example, find intensity values indicating a layer transition with a greater frequency than with original documents. It is likewise possible to evaluate the depth range of the layer transition and to find in the region of the layer transition in the case of a manipulated security document an accumulation of intensity values or intensity value changes which do not correspond to a layer transition.
• the depth values, at which intensity values or intensity value changes which in each case via a comparison of a
• Intensity values of adjacent spatial positions in the security document are detected, occur above a threshold or within a limited by an upper threshold and a lower threshold value range, in terms of their Frequency evaluated to determine deviations and / or reconciliation of one or more expected statistical distributions, and from this the
• Section for example, a depth value range
• Cross section area the depth values to which intensity values of a value range are assigned, or depth values which have intensity value changes of a value range
• Range of values are assigned, are approximated with respect to their assigned positions along the at least one distance or curve by a predetermined parameterized function of the position and the verification decision is made on the basis of the derived parameters in the approximation.
• Security document as a security feature, for example, in a finished
• Display area are displayed.
• Evaluation is coupled to one of the at least one depth profile and further depth profiles for further positions on the surface of the
• Security document formed cross-sectional area is displayed, is preferably designed so that it provides such a colored representation. It should be noted that the colors are not correlated with the colors with which the security features may be stored in the security document. They are only for easier
• Fig. 1 is a schematic representation of a verification device
• FIG. 2 is a schematic representation of a section of a layer structure of a security document into which information by means of a
• 3a, 3b schematic representations for explaining a security feature, which is formed via an introduced and then filled-in recess
• Fig. 4 is a schematic representation of a derived from depth profiles
• Fig. 5 is a schematic representation of a depth profiles of a
• Fig. 6 is a schematic representation of a statistical evaluation for a
• FIG. 7 graphical representation of a corresponding statistical evaluation
• FIG. 9 shows a schematic representation of a statistical evaluation analogous to that according to FIG. 8 for a forged security document.
• Depth values, a depth value range are plotted against the assigned positions on the surface and a parameterized function of the position is adapted to the depth values.
• a verification device 1 is shown schematically.
• This comprises a white light interferometer 2.
• the white light interferometer 2 comprises a light source 3 which emits broadband light 4 with spatial coherence.
• the light 4 is first expanded by an optical element 5.
• This then applies to a beam splitter 6.
• the beam splitter allows part of the light 4r to enter a reference arm 7, at the end 8 of which there is a mirror 9 as a reflector.
• This is movably mounted on an actuator 10.
• the actuator 10 can linearly shift the mirror 9 such that a length l r of the reference arm can be varied.
• a further part of the light 4m is directed into a measuring arm 11.
• the measuring arm 1 1 is formed on a example as a glass plate
• Document recording 12 a security document 13 arranged as a measurement object.
• the reflected light 4mR on the surface 15 and in the volume 16 in the interior of the security document 13 in the measuring arm 1 1 is superimposed on the beam splitter 6 with the light 4rR reflected back from the reference arm 7 by the mirror 9 and guided onto a detector 14.
• the detector 14 includes a plurality of photosensitive sensor elements (not shown).
• the beam guidance for three positions P1, P2, P3 is shown on a surface 15 of the security document 13.
• the length l r of the reference arm 7 is varied.
• Corresponding, equally long measuring arm lengths l m extend from the surface 15 into the volume 16 of the security document.
• the time-resolved interference signals are fed to a control and data acquisition device 17, which uses the measured values of each measuring element to determine a depth profile for the corresponding position P 1, P 2, P3 determined along examination directions 19-1 to 19-3.
• the examination directions 19-1 to 19-3 are set by the direction of the light 4m at the corresponding positions P1 to P3. It is understood that depending on the illumination of the
• Document 13 and a resolution of the detector 14 depth profiles for more positions along a distance 20 or, if the light 4 is widened flat, can be detected and evaluated for distributed over a surface positions at the same time.
• the control and data acquisition device 17 controls the actuator 10, with which the mirror 9 is displaced linearly in order to vary the reference arm length l r and herewith the corresponding measuring arm length l m .
• the acquired measurement data which represent interference signals, are evaluated by the control and data acquisition device 17 in order to create the associated depth profiles for the individual positions P1 to P3. This is done according to algorithms known for optical coherence tomography.
• a depth profile for a position includes the corresponding values for the depth values along the examination direction
• Depth value is set. In an evaluation device 21, the depth profiles are then evaluated.
• the control and data acquisition device 17 can with the
• Evaluation device 21 may be combined in one device. Both may be implemented individually or collectively as a program-controlled device. Alternatively, at least the control and detection device 17 may be implemented purely in hardware.
• the verification device 1 comprises In addition, a display device 23, which comprises a freely programmable display surface 24, on which, for example, a derived from depth profiles cross-sectional area 25 is shown. This is shown schematically in FIG. To recognize are
• the verification device may include a storage device 26 in which default data, for example for certain depth profiles, statistical key figures or exemplary cross-sectional areas are stored, which can be used for comparison with determined depth profiles, cross-sectional areas or static evaluations to verify the particular security document under investigation. It is likewise possible for the evaluation device to comprise an interface 27 via which
• Default values can be retrieved from a database. It is equally possible to output measurement results and / or a verification decision via the interface 27, which can be designed as a wired interface or as a radio interface, etc.
• FIG. 2 schematically shows a detail of a security document 12, which is formed from three different substrate layers 31, 32, 33.
• information is coded by ink jet printing.
• On the middle substrate layer 32 three printing pixels 34, 35, 36 are printed. In this case, a part of the printing ink is diffused into the middle substrate layer 32 and the underlying substrate layer 33.
• the substrate layers 31 to 33 for example, in a lamination process to a document body 40 assembled.
• Investigation of a depth profile is the significant extent not only in the lateral direction 37, but also in the vertical direction 38, which is oriented perpendicular to the substrate layer surface 39 of the substrate layer 32, perceptible.
• the information stored in the document body 40 can thus be distinguished from information applied by another printing process in which no or less pronounced diffusion of the colorant into the substrate layers 32, 33 takes place.
• Fig. 3a and 3b further sections of a document body 40 are shown schematically.
• Fig. 3a it is shown that in the document body 40, first, a conical recess 41 is introduced.
• the individual substrate layers 31 to 33 are preferably all made transparent and provided here only for reasons of simplified representation by means of different hatching. The However, substrate layers may have different refractive indices.
• Fig. 3b the finished document body is shown, in which the conical recess 41 is filled with a preferably also transparent filler 42.
• Refractive index of the filling material 42 preferably differs slightly from the
• the filled recess 41 can be based on the changes in the original levels
• a cross-sectional area 25 formed on the basis of several depth profiles arranged next to one another is shown schematically.
• X-axis are the
• the assigned intensity values are graduated in color or gray scale.
• the intensity values assigned to a position for the different depth values represent a depth profile. In the illustrated example, only intensity values that are characteristic for transitions of one are shown for the sake of simplicity
• cross-sectional area representation differs significantly from a cross-sectional representation, as shown in Fig. 5, in which a representation for a similar security document is shown by way of example, which does not include the padded conical recess.
• a representation for a similar security document is shown by way of example, which does not include the padded conical recess.
• the surface 15 and the two layer boundaries 44, 45, which are not modified, can be clearly seen.
• the frequency as a function of the assigned depth value we obtain for the document without the filled recess, for example, a view as shown in Fig. 6.
• Layer transitions 44,45 can be assigned.
• FIG. 7 shows the same statistical evaluation for the security document with the filled conical recess. Again, the three elevations 53-55 attributable to the surface 15 and the layer boundaries 44, 45 can be seen, but in addition, over a wide depth range 56, a finite number 57 of intensity values caused by the conical walls 43 running obliquely through the document can be seen are (see Fig. 3b).
• FIGS. 8 and 9 show statistical evaluations in which the intensity values occurring in a predefined depth range are plotted as a function of their frequency. While in a verification of a non-manipulated layer boundary (Fig. 8) almost exclusively the one layer transition
• characterizing intensity values 61 are in the distribution of Fig. 9 corresponding to a document having a manipulated layer boundary in the depth region around the layer boundary not only the one layer transition
• Another evaluation may provide that, for example, the depth values, a depth value range 71 (see Fig. 4), which intensity values or
• Intensity value changes above a threshold or within a threshold
• a resulting graph is shown.
• a parametrized function 72 of the position f (x, t1, t2, a, b, c) is adapted to the depth values.
• a comparison of the parameter values with specifications thus makes verification possible. It is understood that only exemplary evaluations are described here. Of course, the individual evaluations can be carried out in combination and complex evaluations can be carried out in order to obtain different ones
• the individual features described may be used in any combination to carry out the invention.

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• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Computer Vision & Pattern Recognition (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Inspection Of Paper Currency And Valuable Securities (AREA)
• Credit Cards Or The Like (AREA)

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• 2011
  • 2011-05-16 DE DE102011075943A patent/DE102011075943A1/de not_active Withdrawn
• 2012
  • 2012-05-10 EP EP12720181.2A patent/EP2710564B1/de active Active
  • 2012-05-10 WO PCT/EP2012/058646 patent/WO2012156274A1/de active Application Filing
  • 2012-05-10 CN CN201280023559.5A patent/CN103534735B/zh active Active

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